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[aprssig] Helmet Antenna - dont bother.

Chris Rose kb8uih at sbcglobal.net
Mon Mar 7 04:13:52 UTC 2005

We have used a bike flag with a twinlead j pole taped
to them for voice and APRS on a more or less straigt
40 mile route and had excellent voice results, the
APRS needed a digi in the middle that we didn't have
at the time.  The height of the flag helped I think. 
Short coax run of about 5' or so.  Headset on the
rider and ht strapped to the handlebars or frame of
the bike.


--- Robert Bruninga <bruninga at usna.edu> wrote:

> Today I was tail-bike on a marathon.  
> Lesson:  Dont bother with a helmet antenna
> for voice.  (APRS maybe, but not for just voice).
> I took one of those tiny 19" mag mount
> whips with a small base (like a kisses chocolate
> piece)
> stuck it inside the helmet protruding up through the
> air holes, covered the inside with aluminum foil and
> then let a can lid stick to the bottom of the
> magnet.
> I also, carried an identical HT with its own
> long whip.  Conclusion was generally no difference
> after lots of side-by-side tests...
> Therefore, dont bother.
> An HT held to my mouth with a similar 19" whip is 
> going to work similarly as a 19" whip on the helmet
> at 
> the same height.  I had just hoped that the slightly
> better ground  plane might work better than the HT
> with 
> no real  counterpoise.... dont bother.
> Now, for APRS where you are not holding the HT to
> your mouth, then maybe the extra height and lack
> of body blockage is worth it.
> Just 2 cents...
> Bob
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